toolchain: musl: fix symlink for ldd

ld-musl-*.so* is a symlink "broken" for the hostsystem, so wildcard
will skip it, causing LD_MUSL_NAME to empty and the ldd symlink pointing
to ../../lib directly.
This causes sysupgrade failing to copy any linked libaries and
consequently failing to run anything after switching to ram disk.

Fix this by creating a symlink directly pointing to where ld-musl-*.so*
points to.

Signed-off-by: Jonas Gorski <jogo@openwrt.org>

SVN-Revision: 43314

package/libs/toolchain/Makefile

@@ -466,7 +466,7 @@ ifeq ($(CONFIG_EXTERNAL_TOOLCHAIN),)
 		$(1)/lib/
   endef
 
-  LD_MUSL_NAME = $(notdir $(firstword $(wildcard $(TOOLCHAIN_DIR)/lib/ld-musl-*.so*)))
+  LD_MUSL_NAME = $(notdir $(firstword $(wildcard $(TOOLCHAIN_DIR)/lib/libc.so*)))
 
   define Package/musl/install
 	$(INSTALL_DIR) $(1)/lib $(1)/usr/bin